scsp: add "slot" example

This demonstrates the most basic possible SCSP usage.

Strangely this does not work in Kronos, only in mednafen and on real
hardware. I'd like to find a hack, if possible, that fixes Kronos
playback.

Makefile

@@ -20,6 +20,9 @@ endef
 %.bin.o: %.bin
 	$(BUILD_BINARY_O)
 
+%.pcm.o: %.pcm
+	$(BUILD_BINARY_O)
+
 %.data.pal.o: %.data.pal
 	$(BUILD_BINARY_O)
 
@@ -69,6 +72,14 @@ wordle/wordle.o: wordle/word_list.hpp
 
 wordle/wordle.elf: wordle/main_saturn.o wordle/wordle.o wordle/draw.o sh/lib1funcs.o res/dejavusansmono.font.bin.o common/keyboard.o common/draw_font.o common/palette.o
 
+scsp/sine-44100-s16be-1ch.pcm:
+	sox \
+		-r 44100 -e signed-integer -b 16 -c 1 -n -B \
+		$@.raw \
+		synth 1 sin 440 vol -10dB
+	mv $@.raw $@
+
+scsp/slot.elf: scsp/slot.o scsp/sine-44100-s16be-1ch.pcm.o
 
 # clean
 clean: clean-sh

scsp/slot.cpp

@@ -0,0 +1,43 @@
+#include <stdint.h>
+#include "smpc.h"
+#include "scsp.h"
+
+#include "../common/copy.hpp"
+
+extern void * _sine_start __asm("_binary_scsp_sine_44100_s16be_1ch_pcm_start");
+
+void main()
+{
+  while ((smpc.reg.SF & 1) != 0);
+  smpc.reg.SF = 1;
+  smpc.reg.COMREG = COMREG__SNDON;
+  while (smpc.reg.oreg[31] != 0b00000110);
+
+  for (long i = 0; i < 807; i++) { asm volatile ("nop"); }   // wait for (way) more than 30µs
+
+  scsp.reg.ctrl.MIXER = MIXER__MEM4MB | MIXER__DAC18B | MIXER__MVOL(0xf);
+
+  const uint32_t * buf = reinterpret_cast<uint32_t*>(&_sine_start);
+  copy<uint32_t>(&scsp.ram.u32[0], buf, 44100 * 2);
+
+  scsp_slot& slot = scsp.reg.slot[0];
+  slot.LOOP = LOOP__KYONB | LOOP__LPCTL__NORMAL; // kx kb sbctl[1:0] ssctl[1:0] lpctl[1:0] 8b sa[19:16]
+  slot.SA = 0; // start address (bytes)
+  slot.LSA = 0; // loop start address (samples)
+  slot.LEA = 44100; // loop end address (samples)
+  slot.EG = EG__EGHOLD; // d2r d1r ho ar krs dl rr
+  slot.VOLUME = 0; // stwinh sdir tl
+  slot.FM = 0; // mdl mdxsl mdysl
+  slot.PITCH = PITCH__OCT(0) | PITCH__FNS(0); // oct fns
+  slot.LFO = 0; // lfof plfows
+  slot.MIXER = MIXER__DISDL(0b101); // disdl dipan efsdl efpan
+
+  slot.LOOP |= LOOP__KYONEX;
+}
+
+extern "C"
+void start(void)
+{
+  main();
+  while (1);
+}